Method of and apparatus for making brush contact assemblies



June 15, 1965 J. R. LORCH 3,138,722

METHOD OF AND APPARATUS FOR MAKING BRUSH CONTACT ASSEMBLIES Filed June19, 1961 2 Sheets-Sheet 1 INVENTOR James R. Lorch @EIfiA BY ATTORNEYJune 15, 1965 LORCH 3,188,722

METHOD OF AND APPARATUS FOR MAKING BRUSH CONTACT ASSEMBLIES Filed June19, 1961 2 Sheets-Sheet 2 INVENTOR James R. Lorch BY W w ATTORNEYSUnited States Patent 3,188,722 METHOD OF AND APPARATUS FOR MAKING BRUSHCONTACT ASSEMBLIES James R. Lorch, Pinole, Califi, assignor to SCMCorporation, a corporation of New York Filed June 19, 1961, Ser. No.118,177 5 Claims. (Cl. Z9--155.5)

The present invention relates to methods of manufacturing wire brushcontact assemblies and apparatus used in the method, and morespecifically to a method wherein each brush contact is composed ofmultiple wires.

The multiple brush contact assembly of the present invention isparticularly well adapted for use in the program device as described inmy copending application Serial No. 100,169 filed April 3, 1961, and isadapted to be mounted on a fixed base of the typewriter with thecontacts facing upwardly. The flexible contacts thus positioned maysense perforations in a perforated tape or record member having aplurality of channels and attached to the underside of the typewritercarriage. The wire brushes are electrically isolated from one anotherand are adapted for use as means to program a data processing system inaccordance with the position of the typewriter carriage.

The brush contact assembly as described in connection with the novelmethod of the present invention is similar in many respects to the brushcontact assembly disclosed and claimed in US. Patent No. 3,072,238issued January 8, 196-3, to Gim P. Chan and assigned to the assignee ofthe present invention. A particular shape of the contact brushes asdisclosed in the Chan application provides a smooth slide over theunperfor-ated surfaces of the tape or record member with minimum wearand a smooth camming action into engagement with and out ofa perforationin a card or tape regardless of the direction of relative movementbet-ween the brush assembly and the perforated record member. To achievethe foregoing advantageous wear properties, each brush has been formedfrom a plurality of individual wires having diameters in the order of 5to 20 mils which are secured together at their ends and formed in suchway to prevent crossing of the wires, splaying or turning of the wiresin grooves in which they are mounted.

In the method previously used for forming the contact brush assembly,the contact wires were soldered to a notched piece of copper-cladphenolic. This resulted in all or nearly all of the wires being shortedtogether to form an electrically common brush. The notched pieces ofcopper-clad phenolic were actual parts of the final product and remainedpermanently attached to the contact wires of the brush assemblythroughout all subsequent assembly operations. Problems were thuspresented in the prior method which inherently prevented theconstruction of a contact brush assembly where the brushes wereelectrically isolated, but yet retained all t of the advantages of themultiple wire contact brush assembly as disclosed in theabove-identified Chan application.

The principal object of the present invention is to provide a novelmethod of forming a brush contact assembly of the type wherein eachbrush may be electrically isolated from the other brushes and yetcomposed of a plurality of individual wires.

Another object of this invention is to provide in a method of making acontact brush assembly, an improved method of cutting, locating andpositioning the individual wires for each brush on throw-away supportpost mem bers, and then after formation of the V contacts at the centerof the brushes, of securing the ends of the brushes to a phenolicinsulating material which serves as the "ice base member. After thebrushes are secured to the base member, the throw-away support postmembers may be cut off thereby leaving each multiple wire brush in itsdesired position on the brush contact assembly with each of the brusheselectrically isolated from the other brushes.

A further object resides in the step of soldering the wire as cut fromthe coil to the throw-away support post members and causing the solderto run along the wires toward the center of the brush a distancesufiicient so that when the throw-away post members are cut off, thewires forming each individual brush remain soldered together to be bothelectrically and mechanically secured to each other at the opposite endsof the brush assembly.

A still further object of the invention is to provide an improved jigassembly wherein the jig assembly has slotted guide members to serve asmeans for positioning and orienting the wires as they are cut from acoil and slots for receiving the throw-away post members on which thecontact wires are initially soldered during the assembly operation.

These and other objects of the invention will become more fully apparentfrom the claims, and from the description as it proceeds in connectionwith the drawings wherein:

FIGURE 1 is a plan view of the contact brush as-. sembly of the presentinvention shown in its condition just prior to the time throw-away postmembers 114 are removed;

FIGURE 2 is a side elevation view of the contact brush assembly ofFIGURE 1;

FIGURE 3 is a pictorial view of the solder jig assembly showing thethree wires which make up one brush in position for soldering;

FIGURE 3A is a partial section of the solder jig assembly of FIGURE 3showing the position of the wires when they are soldered as seen alonglines 3A3A;

FIGURE 4 is a side elevation view of the jig assembly of FIGURE 3 FIGURE5 is an elevation view of a two piece die assembly used for forming theV portions on the brush contacts.

Referring now to the drawings and more particularly to FIGURES l and 2,the contact brush assembly 20 made in accordance with the presentinvention may have a channel shaped base member 22 formed of a suitableelectrical insulating material such as phenolic resin having twoupwardly extending edge portions 28. The upper surfaces 34- of edgeportions 28 lie in a common plane and may be provided .with shallowparallel grooves into which the ends 23 of the contact brushes 40 aresecured. The contact brushes 40 are thus insulated from each other onboth ends of the contact brush assembly 20.

Suitable apertures 31 and 32. may be provided in base 22 for mountingbrush assembly 20 on a piece of equipment such as a typewriter. A covermember 29 of a suitable plastic insulating material is secured as by anadhesive on opposite end surfaces 34 of base member 22 and is providedwith elongated slots 30 through which the central V shaped portions 44of brushes 40 extend. The side edges of slots 30 prevent the central Vportion 44 from deflecting laterally to thus assure that each brush 4%retains its desired alignment.

Each of the individual brushes 40 illustrated in FIG- URES 1 and 2 iscomposed of three beryllium copper wires, with each wire having adiameter on the order of 5 to 20 mils. The central V shaped portion 44has a tip 46 which is rounded and smoothed on both sides to ret 3 p ducewear on a perforated record with which the present invention is adaptedfor use.

In an exemplary practical application, the contact brush assembly may bemounted on a stationary part of a typewriter in the manner more fullydisclosed in the Chan Patent No. 3,072,238 identified above, invertically spaced relation beneath a perforated program tape of anvprogram tape relative to the perforations with minimum Wear upon the.tape regard-" less of direction of movement of the carriage.

Contact wires, three of which aroused to form each brush 40, are cutfrom a long lengthof wire conventionally shipped from the manufacturerintthe form of a coil.

The first step in the method' of forming. contact Wire groups or brushes40in accordancewith the present in vention is accomplished on theapparatus best illustrated in FIGURES 3 and 4'; The apparatus 100.comprises a solder jig assembly composed of a substantiallyrectangularbase member 102 having anupper surface 104 ,cu'rved throughout itslongitudinal extent with a radius corresponding approximately'to'theradius of curvature of the wire coil, not shown. 7 Adjacentthelongitudinally. opposed ends of the base member 102 is a pair ofparallel, laterally extending slots 106 which are spaced a preselecteddistance apart greater than the length of the wires usedrin the finishedcontact assembly block. 20. Spaced inwardly from slots 106jis anotherpair of parallel slots 108. The. distance between slots 108 maybesomewhat less than thelength of the wires in the finished 4 side-by sideparallel relation with their respective opposite ends, 23 'dr'oopeddownwardly; The three contact wires 5 for each brush 40 are thenpositioned in theirside-by-side relation on the curved surface 104 ofsolder jig assembly through a pair of axiallyaligned slots 112 in guidemembers 110. The three contact wires in a single guide slot 112 on thesolder jig assembly 100'are then secured'as by soldering at one end tothe adjacent post member 114.

During the solderingioperation, solder is caused to run up the contactwires to slots 112 in guide members 110.

'As guide members 110 are of aluminum, the solder does not adhere tothem. This secures the contact wires of each brush together along alength of the brush'to prevent splay, crossover or turning of theindividual wires vrelative to one anotheri I With the unsoldered ends ofthe contact wires freely drooped across surface 104 and support post'114solder is then applied to them and-their support post 114. Again thesolder'is run up the contact wires to the location of guide member 112..This foregoing step of soldering is v performed without the applicationof a tension force on the wires as used in the method disclosed in theGim Chan patent identified above, and at a time when the wires areeachdisposed freelytonthe solder jig assembly 100 ,in'side by siderelation with their natural curvature onforming'to that of theuppercurved surface of the base member 102 throughout their lengths.

After all of contact brushes'40 have been secured at both ends to andbetweenthe support post members114, screws 120 are'loosenedand-thegcontactbrush sub-assembly thus formed is removed from the solderjig assembly. ,The next step in the; manufacture of the contact brushesisthe formationrofa'V in the "central portion of the contact. brusheswhich is accomplished on the following contact assembly block20.Guide'members .110 may be 1 secured in the receivingslots 108 by anadhesive or if desired by fasteners to permitdifferent brusharrangements and spacings to be formed,

, .Ea'ch guide member 1101has slots 112 at pre-selected 7 positions forlocating the Wires in. groups andat positions which determine thegrouping of brushes 40 on brush assembly 20. of FIGURE 1. Slots 112 inguide members 110 are in axial alignment, and each guide slot 112 has awidthsufficient to receive. the three separate wires which form eachbrush 40. vAlso, the bottom surfaee'of each guide slot 112 is preferablyflush with the upper curved surface 104 of the base member 102. It willbe seen,

therefore, that three contact wires are received in the.

guide slots 112 exactly as they fit in side-by-sideabutting relation andconform to the upper curved surface 104 of the base member as thenatural curvature of the contact wires corresponds to the curvature ofupper surface 104 of the base member 102. t

Post members 114 that are loosely received in are; preferably made ofmetal, or at least have an upper metallic surface. Post members 114 aresecured in position' during the initial steps of'forming the brushassembly in slots 106 as by screws 120 which are threaded through bores118. The upper surface of each member 114 is slots 106 substantiallyflush with curved surface 104 of the base member 102 so that the contactwires when placed on upper curved surface 104 of base member102 will bein a position to be easily secured' to'post members 114'by anelectrically conductive bonding agent such as a solder or electricallyconductive paste or cement.

The assembly 'procedureis as follows: after screws 120 are backed off,post members'114' are inserted into the slots 106 and screws 120tightened to hold support posts 7 wire bending die assembly'asshownin'FIGURE 5' in a manner as disclosed and claimed in the Chanpatent. The die assembly may conveniently comprise a base member 200having a length comparable to the length of support post members 114.".Four pins 202 extend upwardly from each of the four corner positions-toserve as guides for upper die member 204. On opposite side walls clampelements 206 and screws 208 which may be tightened maybe providedsouthat support posts-114 are lightly clamped when'contact'wires ofbrushes'40 are at corner edges 210 and 212 "of base member 200. V

r The upper surface of base member 200 has a pair of surfaces '21'4 and216 which slope inwardly :and downwardly. At the, center, aninverted Vsection is pro- -nating in an apex having a small radius of curvature asillustrated. The lower surface of the upper die memher 204 has acomplementary configuration so that when it istpressed downwardly, allof the wire groups are simultaneously forced across the upper surface.Suflicient force is used to cause permanent deformation of the contactbrush forming wire groups 40. Care must be taken at all steps topreventthe-wires in each individual group from crossing; After upper diemember 204 is raised, the wires have a permanent configuration similarto that shown in FIGURE 2. a j

Each' wire in each contact wire group 40 is made the same length,,and byusing only lengths of new'w re that are free of sharp bends, each wireissubstantially equally uniformly internally stressed and has the sameresilience. The brushesthus formed therefore have parallelconfigurations. By forming the Y contact portions after securing theends of the wires to support post members 1-14, the upper curved portion46 (FIGURE 2) of each wire group 40'forming each brush is located alonga straight 'line centrally located :between support posts 114 and at auniform distance from a reference plane such asthe surface of a. programtape backing plate.

7 Afteri'the central V has been impressed in the contact brushes by thedie assembly, the contact 'brush sublassembly' isthen placed on surfaces34 of upwardly extending edge portions 28 of contact carrier block 22shown in FIGURES 1 and 2. Surface 34 is provided with shallow grooveshaving a depth approximately equal to the diameter of the wires and awidth substantially equal to three times the diameter of the wire. Thesegrooves are spaced relative to one another in the same manner as thewire receiving and positioning guide slots 112 of the guide members 110shown in FIGURE 3.

(l'he end portions of brushes 40 where the contact wires are solderedtogether are placed in a groove on surface 34. The wires may then besecured in the grooves by a suitable non-conducting epoxy-adhesivecapable of bonding metal to phenolic and phenolic to phenolic. Suchadhesives are commercially available and wellknown in the art. Coverplate 29 may be placed over the protruding V portions of brushes 40 andsecured by the same adhesive on surfaces 34 over the ends 23 of brushes40.

Metal support post members 114 may then be cut off from the ends of thecontact brushes 23 along lines 240 of FIGURE 1 at each end of the brushassembly.

As a result of this step, each brush 40 becomes electrically separate,though the three wires forming each brush remain electrically connectedtogether by the portion of the solder connection made .at each end ofthe brush assembly and applied along the wires when they were originallysoldered to post members 114. Post members 114 are not used in the brushassembly and may thus be discarded. The ends 23 of brushes 40 may beconnected to various other conductors in any conventional manner.

Advantages of the foregoing method over methods used heretofore residein producing multiple brush contact assemblies where the brushes areelectrically separate, and yet at the same time each brush is composedof a plurality of electrical conductors which are secured together. Toproduce a multiple wire brush having the desired operatingcharacteristics, each wire must be bent to have identical con-tours. Bythe present invention the wires used to form each brush are soldered atone end and then permitted to droop freely across the jig as determinedby the natural curvature of the wire when the lengths of wire are cutfrom the coil rather than being stretched taut as in prior methods,before the other end is soldered. The cylindrical outer surface .104 onjig base 102 and slots 11-2, in guide members 110 facilitate the properdisposition of the lengths of wire so that each will have the sameinitial length and proper orientation.

.In the method of the present invention, support posts 1-1 4 arethrow-away metal strips used solely for initially positioning theseveral brushes and wires forming each brush. .The solder applied topost 114 is caused to run along the wires away from post .114. After theV-shaped contacts are formed, the brush sub-assembly is positioned onthe base of brush contact assembly and the several brushes securedthereto by an adhesive which may have insulation proper-ties. After theadhesive has hardened, the throw-away support posts are cut off to thuselectrically isolate the several brushes of the brush contact assemblyone from the other, but yet the individual wires of each brush remainsoldered together at both ends.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

1. A method of manufacturing a contact brush assembly having a pluralityof brushes, each composed of a plurality of individual wires connectedelectrically together and secured to spaced support members ofinsulating material comprising the steps of: providing a pair of spacedparallel post members having an upper solderable metal surface; placinglengths of wires across the upper surfaces of said post members in apredetermined pattern; soldering the wires to said post members and theindividual wires of each contact brush to each other while in saidpredetermined pattern to form a subassembly, the solder being appliedalong the wires from the position on the post member toward the centerof the contact brush a predetermined distance; bending the wires to formV shaped contact portions at a central position of each contact brush;placing said sub-assembly over said spaced support members of insulatingmaterial; securing opposite ends of each individual contact brush tosaid support members at positions approximately where the individualwires of each brush are secured together; and finally cutting the wireson an end at a position between said support members and said postmembers to remove a post member from the contact brush assembly, saidcutting occurring within said predetermined distance, whereby asubstantial portion of the bonded connection is left intact at least atone end of each group of wires.

2. A method of manufacturing a contact brush assembly having a pluralityof brushes, each composed of a plurality of individual wires connectedelectrically together and secured to spaced support members ofinsulating material comprising the steps of: providing a base memberhaving an upper surface and parallel spaced slots formed in said uppersurface; placing elongated post members having upper metal surfaces insaid slots; placing lengths of wires across the upper surfaces of saidpost members in a predetermined pattern; securing the Wires to said postmembers and the indivdual wires of each contact brush to each other byan electrically conducting bonding agent while in said predeterminedpattern to form a sub-assembly, the bonding agent being applied alongthe wires from the position on the post members toward the center of thecontact brush a predetermined distance; removing the sub-assembly thusformed from the base member by removing said post member from saidslots; bending the wires of said sub-assembly to form V shaped contactportions, at a central position of each contact brush; placing saidsub-assembly over said spaced support members of insulating material;securing opposite ends of each indivdual contact brush to said supportmembers at positions approximately where the individual wires of eachbrush are secured together; and finally cutting the brushes on an end ata position between said .support members and said post members to removethe post members from the contact brush assembly, said cutting occurringwithin said predetermined distance, whereby a substantial portion of thebonded connection is left intact at least at one end of each group ofwires.

3. A method of manufacturing a contact brush assembly having a pluralityof brushes, each composed of a plurality of individual wires cut from acoil of wire having a predetermined diameter and connected electricallytogether and secured in parallel relation at opposite ends to spacedsupport members of insulating material comprising the steps of:providing a base member having an upper surface with elongated slotsformed therein such that the longitudinal axes of said slots areparallel; placing elongated post members having upper metal surfaces insaid slots; said slots orienting said post members such that said uppermetal surfaces are parallel to the free position of wire lengths placedthereon which are cut from said wire coil of predetermined diameter;freely placing lengths of wires cut from said coil of wire across theupper surfaces of said post members in a predetermined pattern; securingthe wires to said post members and the individual wires of each saidpredetermined vpattern to form a siib-assembly,'the bonding agent beingapplied toeachjend of the wires along the wires toward the center ofthe, contact brush a predetermined distance; removing the sub-assemblythus formed from 'saidbase member-by removing said post members fromsaid slots; bending the Wires of said contact brush assembly to form'Vshaped contact portions at the center of each wire; placingsaidsub-'assernbly'over spaced support members of electrical insulatingmaterial; securing opposite ends of each indiviual contact-brush to saidsupport members at positions approximatelywhere the individual wires ofeach brush; are soldered together; and finally cutting the wires'on anend at a position between said support members and said postmembe'rs toremove a post member' fromthe contact brush assembly, said cuttingoccurring within said predetermined distance, whereb'y'a substantial'portionof the bonded connection is left intact at least atone end ofeach group of wires.

4. A method of manufacturing a contact-brush assembly having a pluralityof brushes,1each composed'of a plurality of individual wires cut froma;coil of wire'havv ing'a predetermined diameter, which are connectedelectricallyj together and each secured to parallelsup'port' members ofinsulating material comprising the steps ,of:

providing a base member with anupper-surface having aradius'of'curvatu're corresponding to the radiusof curvature ofsaidtcoil-of wire; elongated-slots havinglparallel axes, and wire guidememberspositioned near and"par-,

allel to a corresponding slot,ysaid wire" guide members having spacedguide slots'with the bottom of said guide slots lying-substantiallyflush with said upper curved'surface; placing elongated post membershaving uppermotallic surfaces in said elongated-slots such that theupper contact brush :to' each other by an electrically conductingbondingagentwhile in tionsat the center of eachwire;'placing said sub-assemblyover said spaced support; members of insulating material and' securingopposite ends of each individual contact brush to said support member,at positions'approximately where the individual wires of each brush aresecured together; and finally cutting the wires off atan end at aposition between said support members and said post members to remove apost member from the contact brush assembly said cutting occurring.within' said predetermined 'distance, whereby;a substantial portion'ofthe bonded connection is left-intact at least atone end of each group ofwires.

5.A method-of manufacturing a contact brush assembly having a pluralityof ibrushes, each composed of a plurality of individual wires connectedelectrically together and secured to spaced support members ofinsula'ting material comprising the steps of: providing a pair 7 ofspaced parallel postmembers; placing lengths of wires across the-uppersurfaces of said post members in a predetermined pattern; forming asub-assembly'by securing I thewires to said post members and theindividual wires of each contact brush to' each otherwhile in saidpredetermin'e'd pattern by means of an electrically-conductivevbondingagent, the bonding agent being applied along the wires from the positionon the post member toward the center of the contact brush apredetermined distance;

bending the wires to form V. sh'apedcontact portions at metallicsurface's o'f saidpostmembers are substantially flush with said uppercurved surface of said base member;

post members from: said elongated slots;" bending the, Wires of saidsub-assembly-to form'V-shapedcontact pora central position of eachcontactbrush; placing said sub-assembly lover saidsp'acedsupporttmembers of insulating material; securing oppositevendsgof each individual contact brush to said support members atpositionsapproximately where the individual wires of each brush aresecured together; and finally cutting the wires on an 'end' at aposition between'said support members and said post members to remove a*post member from the contact brush assembly, said cutting'occurringwithin said predetermined distance whereby a substantial portioriofthe-bonded connection is left intact at least at one end of each groupof wires.

References Citedjby the Examiner v UNITED STATES. PATENTS 2,699,133

WHITMORE WILTZ, Primary Examiner;

JOHN F. CAMPBELLg Examiner. j I

1. A METHOD OF MANUFACTURING A CONTACT BRUSH ASSEMBLY HAVING A PLURALITYOF BRUSHES, EACH COMPOSED OF A PLURALITY OF INDIVIDUAL WIRES CONNECTEDELECTRICALLY TOGETHER AND SECURED TO SPACED SUPPORT MEMBERS OFINSULATING MATERIAL COMPRISING THE STEPS OF: PROVIDING A PAIR OF SPACEDPARALLEL POST MEMBERS HAVING AN UPPER SOLDERABLE METAL SURFACE; PLACINGLENGTHS OF WIRES ACROSS THE UPPER SURFACES OF SAID POST MEMBERS IN APREDETERMINED PATTERN; SOLDERING THE WIRES TO SAID POST MEMBERS AND THEINDIVIDUAL WIRES OF EACH CONTACT BRUSH TO EACH OTHER WHILE IN SAIDPREDETERMINED PATTERN TO FORM A SUBASSEMBLY, THE SOLDER BEING APPLIEDALONG THE WIRES FROM THE POSITION ON THE POST MEMBER TOWARD THE CENTEROF THE CONTACT BRUSH A PREDETERMINED DISTANCE; BENDING THE WIRES TO FORMV SHAPED CONTACT PORTIONS AT A CENTRAL POSITION OF EACH CONTACT BRUSH;PLACING SAID SUB-ASSEMBLY OVER SAID SPACED SUPPORT MEMBERS OF INSULATINGMATERIAL; SECURING OPPOSITE ENDS OF EACH INDIVIDUAL CONTACT BRUSH TOSAID SUPPORT MEMBERS AT POSITIONS APPROXMIATELY WHERE THE INDIVIDUALWIRES OF EACH BRUSH ARE SECURED TOGETHER; AND FINALLY CUTTING THE WIRESON AN END AT A POSITION BETWEEN SAID SUPPORT MEMBERS AND SAID POSTMEMBERS TO REMOVE A POST MEMBER FROM THE CONTACT BRUSH ASSEMBLY, SAIDCUTTING OCCURRING WITHIN SAID PREDETERMINED DISTANCE, WHEREBY ASUBSTANTIAL PORTION OF THE BONDED CONNECTION IS LEFT INTACT AT LEAST ATONE END OF EACH GROUP OF WIRES.